Secondary batteries are used as power sources for electrically-powered equipment, and are built in battery packs, for example. These secondary batteries are charged (recharged) by use of chargers (rechargers). Various kinds of such secondary batteries have been proposed by plural manufacturers.
As disclosed in document 1 (JP 1-319270 A) and document 2 (JP 2004-289897 A), there have been proposed preparing plural adapters respectively corresponding to secondary batteries (battery packs) and connecting one selected from the secondary batteries of the plural types to a common charger by use of a corresponding one of the plural adapters.
With regard to the secondary batteries, charging methods appropriate to the respective secondary batteries are different according to manufacturers thereof and/or their types. For example, the charging method mainly defines a charging current value used in constant current charging (hereinafter, referred to as “CC charging”) and a charging voltage value used in constant voltage charging (hereinafter, referred to as “CV charging”), and there are some charging methods peculiar to respective manufacturers. Note that, in a general process of charging the secondary battery, the CC charging with the predetermined charging current value is performed at first, and when the secondary battery is charged up to about 80%, the CC charging is terminated and subsequently the CV charging with the predetermined charging voltage value is performed.
According to the prior charger mentioned above, it is possible to charge (recharge) the secondary batteries of the plural types by use of the common charger and the corresponding adapter interposed between the secondary battery and the common charger. However, in this case, the charging method is likely to be inappropriate to the secondary battery to be charged (i.e., the CC charging and the CV charging are not performed under appropriate conditions). Not performing the charging under an appropriate condition may cause a harmful effect on the life of the secondary battery and the safety of the charging.